Pressure accumulator plants in which a pressurized stored fluid, in particular air, is stored in a storage volume and when necessary is expanded with the outputting of power in a expansion machine have become known from the prior art. U.S. Pat. No. 5,537,822 has disclosed a pressure accumulator plant in which the stored fluid is heated in a heat exchanger before being expanded. In an embodiment disclosed in said document, exhaust gas from a gas turbine set flows through the heat exchanger on the heat-emitting side. Such a recuperative embodiment of a pressure accumulator plant utilizes the waste heat from the gas turbine set very efficiently. Owing to the indirect heating of the stored fluid, said fluid is not contaminated by aggressive flue gas components. For this reason, for example a derivative of a standard steam turbine, which is only slightly modified, can be used as expansion machine in a highly economical way. In the fixed operating mode of the pressure accumulator plant, such a machine is adapted in the best possible way to the thermal peripheral conditions. However, when the plant starts, there are limits on the temperature gradients which can be implemented in a steam turbine, and this must be allowed for in the starting phase. In an arrangement such as is disclosed in U.S. Pat. No. 5,537,822, for example the gas turbine set must be correspondingly operated over a relatively long time period in accordance with an operating regime which is predefined by the expansion machine, and can therefore only be loaded very slowly, which per se contradicts the operating regime of a gas turbine set, and it is possible to react freely to the power requirements of the electric power network only after a long delay, in order to ensure that the possibility of utilizing waste heat in the expansion machine is capable of coping with the waste heat supply made available by the gas turbine set and the stored fluid expansion machine is not damaged by excessively fast starting up and loading.